1. The Field of the Invention
The invention is in the field of endoscopic instruments and methods for performing endoscopy. More particularly, the invention involves endoscopic instruments that perform the combined functions of mechanical cutting, electrosurgical cautery and/or ablation, and improved aspiration of gaseous bubbles.
2. The Relevant Technology
Endoscopy, a subset of which is arthroscopy, is gaining more and more favor as a less invasive means of diagnosing and surgically treating a wide variety of internal injuries or ailments. Endoscopic surgery is much less invasive than completely opening up the tissue and using conventional cutting tools. The result is greatly shortened patient recovery times, minimal scarring, reduced cost, and elimination of typical pre-operative and post-operative hospital stays.
The endoscope allows a doctor to look directly into a surgical site through a small incision, which allows for minimally invasive diagnosis and observation. Endoscopes include a magnifying lens and coated glass fibers that beam an intense, cool light into the surgical site. The surgical field is viewed on a video monitor that is electronically connected to an endoscopic video camera at the tip of the endoscope.
While viewing the surgical site in the manner described, the surgeon can perform any necessary repair and reconstruction using a separate surgical instrument inserted through a second small incision at the surgical site. The surgical instrument may include a mechanical cutting tool, such as a rotating blade or burr. Such mechanical cutting tools, or shavers, are well-known in the art and require no further explanation. In general, rotating blades are generally used to excise unwanted or damaged soft tissues, while rotating burrs are used to remove harder tissues, such as bone.
In addition to mechanical cutting or grinding tools, electronically powered cutting, cauterizing and ablating electrosurgical tools also allow for less invasive surgical procedures. Electrosurgical devices generally operate by imparting electromagnetic energy at a surgical site. Depending on the frequency of the energy delivered by the lead electrode, such devices can cauterize (i.e., heat seal) blood vessels, cut soft tissues, or ablate (i.e., vaporize) soft tissues. Electrosurgical devices are categorized as either xe2x80x9cmonopolarxe2x80x9d or xe2x80x9cbipolarxe2x80x9d depending on the location of the negative, or return, electrode.
In a xe2x80x9cmonopolarxe2x80x9d device, the return electrode is connected to the patient at a remote location relative to the lead electrode of the surgical device. In this manner, the electrical current generated by application of a voltage potential to the lead electrode passes from the lead electrode through the tissue or blood vessel being cut or cauterized, through the intervening tissue of the patient""s body, and to a grounding pad located remotely on a patient""s body. A substantial portion of the pathway through which the current passes is therefore the intervening tissue of the patient""s body.
In contrast, the return electrode in a xe2x80x9cbipolarxe2x80x9d device is located in the near vicinity of one or more lead electrodes and attached to the same surgical instrument. Examples of multiple-lead bipolar devices are set forth in U.S. Pat. No. 4,988,933, U.S. Pat. No. 5,178,620, U.S. Pat. No. 5,366,443 and U.S. Pat. No. 5,419,767, all to Eggers et al. In general, bipolar devices work by passing varying levels of high frequency electrical energy through individually powered multiple leads and into the tissue to be ablated or cauterized. The current returns to the return, or common, electrode located on the same surgical instrument and connected to a ground by means of an insulated ground wire.
In general, both monopolar and bipolar devices can be used to cauterize, cut or ablate tissue depending on the power of the electromagnetic energy that is produced. When ablating tissues, gaseous bubbles comprising mostly water vapor are formed as a byproduct of ablation. Gaseous bubbles can be problematic because they can obscure the field of vision of the surgeon. In addition, gaseous bubbles can inhibit ablation by displacing the fluid needed to transmit electrical energy. Accordingly, some form of aspiration is typically required to continuously remove the gaseous bubbles from the surgical site.
One way is to provide a separate suctioning (or aspirating) device near the electrosurgical device. However, the use of two separate devices can be unwieldy and cumbersome, and it requires separate incisions for both devices. Moreover, the aspiration hole at the end of the aspiration tube must be kept away from surrounding tissue so as to avoid suctioning onto the tissue, which can plug the opening and prevent aspiration. Larger pieces of detached tissue, such as those that may be removed by mechanical means, can easily plug the aspiration tube, requiring removal and unplugging of the aspiration tube.
A better solution involves surgical instruments that combine a mechanical cutting or abrading tool with an electrosurgical device capable of ablation, together with an integral aspiration device. Surgical instruments combing a rotatable mechanical cutting or abrading tool, an electrosurgical instrument, and an integral aspiration device are disclosed in U.S. Pat. No. 5,364,395 to West, Jr. (xe2x80x9cWest Ixe2x80x9d) and U.S. Pat. No. 5,904,681 to West, Jr. (xe2x80x9cWest IIxe2x80x9d). The West I and II patents describe surgical devices that include a hollow probe, a rotatable cutting or grinding tool disposed at least partially through an opening at the distal end or tip of the hollow probe, and an electrosurgical device comprising at least one electrode disposed on a side of the hollow probe at the distal end. The electrosurgical device may be either monopolar or bipolar as desired. Typically, mechanical cutting or grinding occurs on one side of the probe tip, and ablation, etc. occurs on the other side of the tip. In some embodiments, the cutting tool is hollow and provides a single hole at the end and an internal pathway through which debris and gaseous bubbles can be aspirated.
One advantage of the devices disclosed in the West I and II patents is the ability of the rotatable cutting or abrading tool to break apart or cut pieces of tissue that could otherwise plug or clog the hole. A downside of such surgical instruments is that they only include a single opening at the distal end of the probe for aspiration. This design often results in drag whenever the single opening at the distal end of the surgical device comes in contact with tissue adjacent or opposite to the tissue targeted for ablation, which causes the opening to suction onto or against the tissue. Such drag can inhibit the ability of the surgeon to properly position the distal end of the surgical device before ablation. It can further inhibit the ability to reposition the device during ablation. Such drag therefore hinders effective and accurate movement of the electrosurgical device whenever it is desired to use the electrosurgical device while the cutting or abrading tool is turned off.
An additional problem with the devices disclosed in the West I and II patents is the fact that the opening at the end of the probe is typically on a side of the probe opposite to the side of the electrosurgical device. As a result, the gaseous bubbles must travel around the sides and/or end of the probe in order to enter the opening within the probe. Depending on the location of the endoscope, gaseous bubbles traveling from one side of the probe to the other can continuously obscure the field of view during ablation, thus requiring periodic stoppages of the ablation process in order to allow for the removal of the gaseous bubbles and restore the field of view. The buildup of bubble may also interfere with tissue ablation by displacing the surrounding fluid. In order to effectively remove the bubbles, it may be necessary to reposition the surgical device, causing further inconvenience.
In view of the foregoing, it is readily apparent that improved aspiration means for aspirating gaseous bubbles from the surgical site are needed in order to reduce or eliminate drag between the surgical instrument and surrounding tissue and also in order to more efficiently remove gaseous bubbles from the field of view.
Such surgical instruments and methods for improved bubble aspiration at a surgical site are disclosed and claimed herein.
The present invention encompasses apparatus that combine a mechanical cutting or abrading tool, an electrosurgical device, and a suctioning device. Such apparatus provide for improved aspiration of gaseous bubbles and a reduction of drag during placement and/or repositioning of the surgical apparatus. The invention also encompasses improved methods for removing gaseous bubbles as they are generated in order to maintain an open field of view and also to reduce the accumulation of gaseous bubbles that can inhibit the operation of the electrosurgical device.
The improved aspiration of gaseous bubbles is accomplished by providing one or more aspiration holes near or in close proximity to the electrosurgical device. Because gaseous bubbles have negligible viscosity compared to the aqueous environment in which typical endoscopic procedures are performed, such gaseous bubbles are preferentially and efficiently aspirated and removed through the one or more aspiration holes. The one or more aspiration holes also serve to prevent or reduce drag, which can otherwise occur if the main opening of the surgical device probe touches and suctions onto soft tissues when positioning the surgical device with the mechanical cutting or abrading tool turned off.
In general, the surgical devices according to the invention include a hollow probe with a proximal end attached to a handle and a distal end where a mechanical cutting tool and an electrosurgical device are located. The hollow probe includes a hollow tubular member within which a drive shaft connected to the mechanical cutting or grinding tool is disposed. The cutting or grinding tool (e.g., a rotatable blade or burr) is preferably disposed at least partially within a main opening at the end of the hollow tubular member of the probe. The main opening of the tubular member may be slanted so as to enclose or shield one side of the rotatable cutting or abrading device while being open at the other side so as to leave a portion of the rotatable tool unshielded.
The electrosurgical device is advantageously attached to a surface of the hollow tubular member at or near the distal end of the probe. In the case where the main opening is slanted, the electrosurgical device will be disposed on or near that portion of the hollow tubular member that encloses a portion of the cutting or grinding tool. In this embodiment, one side of the distal end of the probe provides mechanical cutting or abrading and the other side provides electrosurgical capabilities.
The hollow tubular member of the probe not only encloses the drive shaft and, optionally, a portion of the cutting or abrading tool, it also provides a pathway through which fluid, solid debris, and gaseous bubbles can be continuously and/or intermittently be aspirated during the surgical procedure. In some cases, the drive shaft itself may be hollow so as to provide at least a portion of the actual aspiration pathway. In other cases, there may be a space between the drive shaft and the inner wall of the tubular member that provides the main aspiration pathway. Either way, the tubular member generally encloses the aspiration pathway.
Examples of surgical devices that combine mechanical cutting or abrading, an electrosurgical device, and aspiration capabilities are disclosed in U.S. Pat. No. 5,364,395 to West, Jr. and U.S. Pat. No. 5,904,681 to West, Jr. For purposes of disclosing apparatus that combine mechanical cutting or abrading, an electrosurgical device, and aspiration capabilities, the foregoing patents are incorporated herein by reference. As noted previously, one of the problems associated with the devices disclosed in the West I and II patents is that they only include a single opening through which fluids, debris and gaseous bubbles are aspirated. During mechanical cutting or abrading, the large opening associated with the mechanical cutting or shaving tool adequately aspirates and removes solid debris consisting of hard or soft tissue from the surgical site. When the cutting or abrading tool is in operation, the surgical device continuously aspirates pieces of hard and soft tissue as they are removed, together with ambient saline fluid. Tissues are typically aspirated through the main opening of the hollow probe. Larger pieces of solid debris are effectively chopped up and reduced in size by the rotating blade. However, when the mechanical blade or burr is stationary, such as when a surgical device is being initially positioned or when it is desired to only operate the electrosurgical device, continuous aspiration through the single hole at the end of the hollow probe can cause the distal end of the probe to suctionally adhere to soft tissue, thereby causing drag or resistance that can hinder ease of placement and repositioning of the surgical device.
Another problem is the relative inefficiency with which the single opening aspirates gaseous bubbles that may be generated by the electrosurgical device, such as when it is used to ablate soft tissues. During ablation, significant amounts of localized heat is generated, which causes water within the saline environment to evaporate to form gaseous bubbles. Such bubbles can quickly obscure the field of view otherwise provided by the endoscopic camera at the end of the endoscope. In addition, such gaseous bubbles can inhibit ablation by displacing the surrounding fluid used to generate an electrical currect in the vicinity of the soft tissue targeted for ablation. The main opening is not optimally positioned relative to the electrode for aspirating gaseous bubbles produced by the electrode, particularly when it is slanted. In some cases, the opening may be completely closed, thereby inhibiting bubble aspiration regardless of the orientation of the opening.
The present invention solves both problems, namely excessive drag and/or inefficient aspiration of gaseous bubbles, by providing one or more aspiration holes or openings in a side of the tubular member comprising the hollow probe so as to provide at least one aspiration hole in addition to the main opening at the distal end of the hollow probe. The aspiration hole through the side of the hollow tubular member effectively breaks the vacuum that can otherwise form when the main opening at the distal end of the hollow probe brushes against soft tissue. In this way, drag or other problems associated with adhesion of the probe to soft tissue is effectively eliminated, or at least greatly reduced. In order for there to be excessive drag resistance associated with the inventive surgical apparatus, both the main opening and the one or more aspiration holes would have to be simultaneously plugged or blocked by soft tissue at the surgical site, which is much less likely to happen than when the device includes a single opening for aspiration.
The one or more aspiration holes are preferably located in the vicinity of the electrosurgical device (i.e., xe2x80x9cadjacentxe2x80x9d to the electrosurgical device). Locating the one or more aspiration holes adjacent to the electrosurgical electrode generating the gaseous bubbles greatly enhances the efficiency by which gaseous bubbles can be aspirated and effectively removed from the surgical site as they are being formed during, e.g., ablation. Due to the negligible viscosity of gaseous bubbles, they are preferentially aspirated through the one or more aspiration holes compared to the surrounding fluid. The result is a much clearer field of view of the surgical site and reduced displacement of surrounding fluid.
Another aspect of the invention are methods for more efficiently removing gaseous bubbles from a surgical site during, e.g., ablation by the electrosurgical device. By maintaining constant aspiration through the hollow probe, the gaseous bubbles generated by the electrosurgical device are quickly and effectively aspirated through the one or more aspiration holes adjacent to the electrode generating the gaseous bubbles in order to maintain a clear field of view and avoid fluid displacement in the vicinity of the soft tissue targeted for ablation. The ability to more effectively remove gaseous bubbles is possible whether or not the mechanical cutting or abrading tool is rotating.
These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.